There has existed a considerable problem, particularly in the fertilizer spraying industry, relating to adjustment of flow control for the materials being dispensed. There are a variety of chemicals, for example, that may be utilized with spraying equipment. Each chemical includes a preferred application rate. Flow of the chemical may be controlled, at least in part, by placing a sized orifice upstream from each dispensing outlet. In a typical fertilizer spraying implement, for example, an orifice fitting is situated immediately upstream from each spray head, connecting the spray head to a fertilizer delivery manifold. In order to change the flow of fertilizer, it becomes necessary to change the small orifice disk of each fitting. The process, though not complicated, involves a considerable amount of time and frustration. The small circular orifice plates are relatively difficult to handle and, in adverse conditions, can easily be dropped and lost.
It therefore becomes desirable to obtain some form of device that will facilitate changing of orifice size without requiring disassembly and replacement of a single orifice plate.
Various apparatus have been developed including orifice selection capability. However, these apparatus require relatively elaborate sealing procedures in order to prevent leakage of fluid from the vicinity of the orifice selection mechanism. Furthermore, many of these apparatus are relatively complex and may not be easily disassembled for cleaning or repair.
The present device incorporates variable orifice selection features with provisions for selectively sealing the selected orifice in position within the flow line in a simple yet very effective manner.